The present invention relates to devices for delivering, injecting, infusing, administering or dispensing a substance, and to methods of making and using such devices. More particularly, it relates to a device for preventing a flow through a catheter, and more particularly to a catheter formed such that a flow of a fluid through the catheter due to a hydrostatic pressure of the fluid or liquid flowing through, channeled in or conducted through the catheter is blocked or prevented. The present invention also relates to a system comprising such a catheter and an administering device, e.g. an infusion pump.
Known infusion systems store a drug to be administered in a container, usually an ampoule, in which a carrier fluid with the drug dissolved in it—referred to in the following simply as the drug fluid—is situated between a movable stopper and a container outlet. One end, which may be thought of as the rear end, of a catheter is connected to the container outlet. A needle, which is introduced into the human or animal body to administer the drug fluid, is placed on the other, front, end of the catheter and in most cases remains there for an administering period which is often several days, wherein if the container with the drug fluid is situated at a greater height than the front end of the catheter and/or the needle, there exists the danger, if the difference in height between the container and the front end of the catheter is large enough, of the container gradually emptying itself due to the force of the column of fluid.
In insulin therapy using portable infusion apparatus, for example pump apparatus, the catheters used can exhibit lengths of more than 1 m. If the apparatus, including the container, is arranged vertically above the user, for example at night or when showering, a hydrostatic ground pressure of about 0.1 bar is generated, if no other effects—for example friction losses, discharge effects or capillary action—are taken into account in addition to the purely static pressure due to the inherent weight of the drug fluid, and if the density of water is assumed for the drug fluid.
To prevent any undesirable discharge due to the pressure of the column of fluid, the wall friction between the stopper, which is accommodated in the container such that it can slide freely, and the container wall could be increased; however, this would incur other disadvantages. Another solution would be to fix the stopper to the driven member of an infusion pump, such that the stopper prevents the surface of the fluid from dropping in the container and so prevents it from emptying itself. Known systems involving screwing the stopper to the driven member. This, however, increases the cost of the apparatus. Also, this solution cannot be used with prefabricated ampoules, since the stopper is not prepared for a screw connection.
International application WO 97/02059 relates to an infusion pump comprising a pump casing and a safety valve which is intended to prevent delivery of the drug from being caused by gravity alone. The connecting casing of the pump is detachably fastened to the pump casing. Also, its upstream end is connected to a sack-like drug reservoir via a catheter and an inlet connector.
International application WO 95/16480 discloses an infusion device comprising a drug container, a catheter leading away from it, a clamp arranged on the catheter, a pump connected to the catheter, another catheter leading from the pump to the patient, and a safety valve arranged in said other catheter. By means of the clamp for the first catheter and the safety valve, the intention is to prevent the drug fluid from being undesirably conveyed due to gravity.
EP 0 882 466 A2 discloses a device for administering, in particular infusing, a drug fluid in doses, comprising a container from which the drug fluid is displaced in doses through an outlet when a stopper is advanced, to administer it, and comprising a catheter which is connected to the container at the outlet, wherein the front end of said catheter facing away from the outlet is or can be connected to an administering needle, wherein a valve is arranged between the outlet and the administering needle in a flow cross-section of the drug fluid, and the valve only allows a flow toward the front end of the catheter when the fluid pressure acting in this direction is greater than a pressure bearing on the valve as a result of the inherent weight of a column of fluid in the device, to prevent the container from emptying itself.